1. 6LOWPAN A Wireless Extension of the Internet
Great Option for IOT

2. 6LOWPANIPv6 over Low-power Wireless Personal Area Network.
This is a Networking Technology or adaption layer that IPv6 can be applied even to the small link layer frames defined by IEEE
Open standard defined in RFC 6282 by IETF
Important feature 6LoWPAN originally designed to support IEEE in 2.4GHz.
But now can be adapted for variety of networking media like Low power RF, Bluetooth smart and low power Wifi.

3. 6LOWPAN NETWORK ARCHITECTURE
Wireless Embedded Internet created by connecting islands of wireless embedded devices each island being stub network on the internet.
Overall 6LOWPAN architecture is presented in the fig
Stub network Network which IP packets are sent from or destined to but doesnot act as transit to other network

4. Three different kinds of LoWPANs have been defined.
6LOWPAN  made up of low power wireless networks which are IPv6 subnetworks.
Three different kinds of LoWPANs have been defined.
Simple LOWPANs
Extended LOWPAN &
Adhoc LOWPAN
A LOWPAN is the collection of 6LOWPAN nodes which share common IPv6 address prefix of where a node is in a LoWPAN its IPv6 address remains the same.
A Simple LOWPANs  connected through one LoWPAN Edge Router to another IP network.
Backhaul linkPoint to point (e.g GPRS)
Backbone Link Shared
An extended LoWPAN encompasses LoWPANs of multiple edge router along with a backbone link interconnecting them.

5. LOWPAN connected to other IP networks through edge routers.
Edge Router Route traffic in and out of LoWPAN
Edge routers have management functions and Overall IT management solutions.
Multiple Edge routers are used in same LOWPAN they share a common backbone link.
A LOWPAN consists of nodes which play role of router or host along with edge routers.
For efficient network operation nodes register with an edge router.
ND Neighbour Discovery defines how hosts and routers interact with each other on same link.
LoWPAN nodes participate in more than one LoWPAN at the same time called multi-homing

6. Multihop Mesh topology within LoWPAN achieved through link layer forwarding or using IP routing
Each LoWPAN is identified by a unique IPv6address and capable of sending and receiving IPv6 packets
LoWPAN nodes support ICMPv6 traffic such as Ping and use UDP as transport

7. Simple and Extended LoWPAN
Simple and Extended LoWPAN can communicate through edge router.
Difference between two is the existence of multiple edge router and share same IPv6 Prefix also a common backbone link.
Multiple LoWPAN can overlap each other.
A LoWPAN edge router typically connected to internet through cellular or DSL

8. 6LoWPAN does not require infrastructure to operate
Ad hoc LoWPAN:
One router must be configures to act as simplified edge router.
It implements two basic functionalities
Unique local unicast address (ULA) generation
 Handling 6LoWPAN ND registration functionality

9. SYSTEM STACK OVERVIEW 6LoWPAN radically changes IoT environment.
Already discussed devices such as Zigbee,Bluetooth need a complex application layer gateway to connect to Internet.
6LoWPAN solves by introducing adaption layer between IP stack link and network layers to enable transmission of IPv6 datagrams over IEEE radio links.

10. OSI MODEL,A Wi-Fi stack example and the 6loWPAN Stack

11. PHYSICAL LAYER
Converts Data bits into signals that are transmitted and received over the air.
Two important standards IEEE e and IEEE g
IEEE e provides enhancements such as time slotted channel hopping (TSCH) and coordinated sampled listening (CSL).
IEEE g aims to provide an additional range of RF bands to enable worldwide use in Sub 1-GHz frequency bands

12. Data Link Layer
Provides a reliable link between two directly connecting nodes by detecting and correcting errors that occur in physical layer.
Data link layer includes MAC which provides access to media , Using CSMA-CA
This layer hands data framing
Adaptation layer provides adaptation from IPv6 to IEEE

13. Network layer
Addresses and routes data through network over several hops.
IP is the internetworking protocol used to provides all devices with IP address to transport packet.

14. Transport Layer
Generates communication between applications running on devices
Allows multiple applications on each device to have their own communication channel
TCP dominant transport protocol on the Internet.
TCP connection based protocol
UDP Connectionless protocol

15. Application Layer Responsible for data formatting
Application layer HTTP running over TCP,HTTP uses XML
Industry and community have alternative protocols Such as COAP – Constrained application protocol

16. ADAPTATION LAYER
For sending data over MAC and PHY adaptation layer is used
For 6LoWPAN RFC 6282 defines how IPv6 data frame is encapsulated over an IEEE
Main focus 6LoWPAN WG was to optimize the transmission of IPV6 packet over low power and lossy networks.

17. Header compression compresses 40-byte IPv6 and 8-byte UDP headers by assuming the usage of common fields.
Fragmentation and Reassembly
Stateless auto configuration Device inside 6LoWPAN generate their own IPv6 address.This methods avoids Duplicate Address Detection(DAD).

18. HEADER COMPRESSION

19. HEADER COMPRESSION IP Header compression is Status based.
If Point to point connections Stable links
If Multiple hops hop-by-hop compression/decompression
Routing Protocols running in LoWPAN system obtain diversity by rerouting which reduce compression efficiency

20. Header Formats
6LoWPAN uses stacked header and similar to IPv6,extension headers
6LoWPAN header defines capability of each sub-header.
Sub header defined are
 Mesh addressing
 Fragmentation and
 header compression

21. Mesh Addressing Support layer -two forwarding and fragmentation support the transmission of IPv6 MTU.
Fragmentation header is omitted for packets that fit into single IEEE frame.
Fragment Header contains 3 fields
(i) Datagram size Total (un-fragmented) Payload
(ii) Datagram tag identifies set of fragment and match the fragments
(iii) Datagram offset identifies fragments offset within unfragmented payload.
Mesh header includes three fields
(i) hop limit
(ii) source address
(iii) Destination address

22. 6LoWPAN Stacked Header

23. CHALLENGES IN 6LoWPAN
IP connectivity As nodes increase ,necessity for network auto configutation,achieved through IPv6.
Limited Packet SizeApplications using 6LoWPAN support only Small packets
Limited configuration and Management
Service discovery and security
Loacalization Provide information related to nodes , 6LoWPAN networks poses certain challenges such as failure of node due to lack of power ,interference lead to re-routing and re-organisation of the network

24. WIRELESS HART
HARTHighway Addressable Remote Transducer is a communication protocol designed for industrial process measurement and control applications
This is a open standard and vendor independent.
It is called a hybrid protocol it combines analogue and digital communication.
It communicate a single variable using 4-20mA analogue signal and also communicating added information on a digital signal
Analog information travel one way.
Digital information can travel in both directions using HART.

25. Traditional analog derives no easy way to tell if the information sending is valid.
HART will get process variable ,Information item standard in every HART device such as.
1.Device status and diagnostic alert
2.process variable and units
3.Loop current and percentage range.
4.Basic configuration parameters
5.Manfacturer and device tag information.

26. HART WORKING HART  uses a request/reply communication model.
HART does not transmit any information unless a request is sent from host to device.
In Burst mode HART device can send a single piece of information continuously without requested host.
Many control system doesn’t accept HART information in digital form so external multiplexers reading digital signal is used/

27. Wireless HART
Wireless HART can be used on existing wired instrument to collect vast amount of information and provides cost-effective and reliable way to deploy new points of measurement and control
Wireless HART device uses nominal 2.4 GHz transmission frequency using IEEE standard .

28. Wireless HART Network
Wireless HART is a subset of HART industrial instrument communication standard as a ver 7 communicating process data over 2.4 GHz radio waves.
Wireless HART is a wireless mesh network communications protocol for process automation applications.
Each instrument in HART wireless connection is connected through a mesh network.
If instrument far from the gateway or route blocked it is not connect to gateway.
Each device in the mesh network can serve as a router for messages form other devices.
Purpose of mesh network is to provide redundant data pathways in case of device failure or changes in the environment